Wireless communications have become widely used to provide communication of various types of information, including both voice and data information. Accordingly, there is often limited wireless spectrum availability for any particular service provider and/or any particular subscriber. Therefore, it is often important to efficiently communicate information between service providers and their subscribers both to provide subscribers with the information bandwidth they need/desire as well as to allow various service providers to provide services to a reasonably large number of individual subscribers.
Information communication in such wireless communication systems is limited by various factors. For example, cellular system capacity is almost always limited by inter and intra cell interference. In code division multiple access systems, inter-cell interference is usually a dominant factor. Accordingly, it can be appreciated that a simple increase in transmission power will often be insufficient to increase system capacity. Moreover temporal processing such as coding, data compression (such as may be particularly useful in voice communication), and diversity can provide capacity increases only to a limited extent, which in many communications systems today have been substantially reached. Accordingly, system configurations which provide interference reduction, thereby allowing an increase in capacity, are desirable.
In some predominately data communication systems forward link (or downlink) bandwidth substantially limits capacity. For example, in wireless communication systems providing Internet or similar access, forward link bandwidth is often saturated with large volumes of data being provided by the network to the subscribers while the reverse link (or uplink) carries comparatively little data. Accordingly, in such systems the forward link may present a bottleneck.
For example, a personal digital assistant (PDA), such as a PALM PILOT available from Palm Computing or an IPAQ available from Compaq Computer Corporation, may be utilized with a wireless modem to provide a subscriber with mobile Internet or other data access. Using such a wireless system, a subscriber may be traveling and, desiring information with respect to particular types of restaurants near by, may access the PDA for relevant information. Accordingly, by providing relatively little information in the reverse link, such as a present location and a type of restaurant desired, a large amount of data may be returned in the forward link, such as a list of all nearby restaurants meeting the parameters in addition to directions to the restaurants, the hours of operation of the restaurants, and/or bills of fare for the identified restaurants.
Therefore, should be appreciated that in network systems the required capacity is often not a function of the number of potential subscribers, but instead the data capacity requirements may be virtually unlimited. This conclusion is particularly valid in light of recent situations where Internet service providers (ISP) have provided higher data throughput which is very quickly consumed by existing subscribers. Accordingly, system configurations which increase forward link capacity in such systems, such as may be provided at least in part through interference reduction, are desirable.
Wireline solutions which addresses the asymmetric behavior of such data communications include cable modems and asymmetrical digital subscriber line (ADSL). For example, a cable modem system provides bandwidth on the order of 2 to 3 megabits per second in the downlink with only about 120 kilobits per second on the uplink.
Wireless solutions have also been developed to address asymmetric data communications, such as the CDMA2000 1×EV (or high data rate (HDR)) specification for code division multiple access (CDMA) developed by Qualcomm. According to this specification optimization of the forward link is attempted through the subscriber units monitoring a common pilot signal being broadcast from the base station (typically provided for handoff determinations between sectors and/or cells of the communication network) and providing information regarding this common pilot to the base station in the reverse link. More specifically, according to the HDR standard, each subscriber unit will monitor a common pilot being broadcast throughout the whole sector by the base station and each subscriber unit gradually sends back the quality or receive strength of the common pilot signal to the base station. Accordingly, each subscriber unit will periodically report the strength of the common pilot as received by that subscriber unit. Using this information, the HDR base station may determine the particular subscriber units currently in a position most likely to be suitable for high data rate transmission in the forward link, i.e., the subscriber units reporting a strong common pilot signal may be provided with high data rate transmissions while the remaining subscriber units may be passed over for a subsequent epoch when they are reporting a strong common pilot signal.
As can be appreciated from the above discussion, the forward link of the described HDR specification results in a time division multiple access (TDMA) sharing of a single wide sector beam in the forward link. Accordingly, one or more of the subscriber units may be provided high data rate transmission in the forward link while other ones of the subscriber units in the same sector are provided no forward link data transmission. However, because data delivery is typically less time critical than voice data, the latency (sometimes on the order of several seconds) of this solution is often acceptable, although undesired.
A need therefore exists in the art for systems and methods which are adapted to provide high bandwidths and/or high data rates in the forward link of wireless communication systems. A further need exists in the art for systems and methods which provide high bandwidths and/or high data rates while optimizing utilization of available spectrum. A still further need exists in the art for systems and methods providing high bandwidths and/or high data rates to minimize data communication latencies associated therewith.